U.S. patent application number 13/945943 was filed with the patent office on 2014-01-23 for semiconductor device, driving mechanism and motor driving control method.
The applicant listed for this patent is LAPIS SEMICONDUCTOR CO., LTD.. Invention is credited to TAKASHI YAMASHITA.
Application Number | 20140021892 13/945943 |
Document ID | / |
Family ID | 49945999 |
Filed Date | 2014-01-23 |
United States Patent
Application |
20140021892 |
Kind Code |
A1 |
YAMASHITA; TAKASHI |
January 23, 2014 |
SEMICONDUCTOR DEVICE, DRIVING MECHANISM AND MOTOR DRIVING CONTROL
METHOD
Abstract
A semiconductor device that controls a motor driving device. The
semiconductor device includes: a position detection section that
detects changes in a turning position of a rotor provided at a
motor and outputs detection signals corresponding to the changing
turning position; a first switching section that, in accordance
with the detection signals, outputs ground switching signals, which
switch which end portion of a coil is connected to a ground side,
to a first switching circuit; and a second switching section that,
in accordance with the detection signals, outputs connection
switching signals, which switch which end portion of the coil is
connected to a driving power supply side, to a third switching
circuit that controls the switching of connections between the end
portions of the coil and the driving power supply side by a second
switching circuit.
Inventors: |
YAMASHITA; TAKASHI;
(YOKOHAMA, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LAPIS SEMICONDUCTOR CO., LTD. |
YOKOHAMA |
|
JP |
|
|
Family ID: |
49945999 |
Appl. No.: |
13/945943 |
Filed: |
July 19, 2013 |
Current U.S.
Class: |
318/400.22 ;
318/400.37 |
Current CPC
Class: |
H02P 6/14 20130101; H02P
6/34 20160201; H02P 6/24 20130101 |
Class at
Publication: |
318/400.22 ;
318/400.37 |
International
Class: |
H02P 6/14 20060101
H02P006/14; H02P 6/24 20060101 H02P006/24 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 23, 2012 |
JP |
2012-162939 |
Claims
1. A semiconductor device that controls a motor driving device, the
motor driving device including: a first switching circuit that
switches which of end portions of a coil provided at a motor is
connected to a ground side; and a second switching circuit that
switches which of the end portions of the coil is connected to a
driving power supply side, and the semiconductor device comprising:
a position detection section that detects changes in a turning
position of a rotor provided at the motor and outputs detection
signals corresponding to the changing turning position; a first
switching section that, in accordance with the detection signals,
outputs ground switching signals, which switch which end portion of
the coil is connected to the ground side, to the first switching
circuit; and a second switching section that, in accordance with
the detection signals, outputs connection switching signals, which
switch which end portion of the coil is connected to the driving
power supply side, to a third switching circuit that controls the
switching of connections between the end portions of the coil and
the driving power supply side by the second switching circuit.
2. The semiconductor device of claim 1, wherein the first switching
circuit includes: a first ground switching section that, when a
first ground switching signal for switching a direction of current
flowing in the coil of the motor to a first direction is inputted,
switches a first end portion of the coil from being connected to
the driving power supply side to the ground side; and a second
ground switching section that, when a second ground switching
signal for switching the direction of the current to a second
direction, which is opposite to the first direction, is inputted,
switches a second end portion of the coil from being connected to
the driving power supply side to the ground side, the second
switching circuit includes: a first power supply switching section
that, when a first power supply switching signal for switching the
direction of the current flowing in the coil of the motor to a
first direction is inputted, switches the first end portion from
being connected to the ground side to the driving power supply
side; and a second power supply switching section that, when a
second power supply switching signal for switching the direction of
the current to a second direction opposite to the first direction
is inputted, switches the second end portion from being connected
to the ground side to the driving power supply side, and the third
switching circuit includes: a first signal input section that
inputs the first power supply switching signal to the first power
supply switching section; and a second signal input section that
inputs the second power supply switching signal to the second power
supply switching section, and wherein the motor driving device, by
alternatingly performing switching to switch the connection state
of the first end portion from the driving power supply side to the
ground side and switch the connection state of the second end
portion from the ground side to the driving power supply side, and
performing switching to switch the connection state of the first
end portion from the ground side to the driving power supply side
and switch the connection state of the second end portion from the
driving power supply side to the ground side, switches the
direction of the current flowing in the coil and drives the motor,
the first switching section detects changes in the turning position
of the motor, inputs the first ground switching signal to the first
ground switching section in accordance with a first detection
signal, which corresponds to a change of the current flowing in the
coil to the first direction, such that the current flowing in the
coil flows in the first direction, and inputs the second ground
switching signal to the second ground switching section in
accordance with a second detection signal, which corresponds to a
change to the second direction, such that the current flowing in
the coil flows in the second direction, and the second switching
section inputs a first connection switching signal to the first
signal input section in accordance with the first detection signal
such that the current flowing in the coil flows in the first
direction, and inputs a second connection switching signal to the
second signal input section in accordance with the second detection
signal such that the current flowing in the coil flows in the
second direction.
3. The semiconductor device of claim 1, wherein the output of the
ground switching signals by the first switching section and the
output of the connection switching signals by the second switching
section are delayed by pre-specified durations from the output of
the detection signals.
4. The semiconductor device of claim 1, wherein the output of the
ground switching signals by the first switching section is delayed
by a pre-specified duration from the input of the detection
signals, and the second switching section outputs the connection
switching signals when the first switching section outputs the
ground switching signals.
5. The semiconductor device of claim 1, wherein the first switching
section outputs the ground switching signals to switching elements
that are provided at the first switching circuit and used for
switching the connections, the switching elements connecting the
coil to the ground side, and the first switching section outputting
PWM pulses that control to turn the switching elements on and
off.
6. The semiconductor device of claim 1, further comprising: an
overcurrent detection section that outputs an overcurrent detection
signal when the current flowing in the motor exceeds a
pre-specified value; and an emergency stop section that, in
accordance with the overcurrent detection signal outputted from the
overcurrent detection section, short-circuits the two ends of the
coil.
7. The semiconductor device of claim 6, wherein the emergency stop
section outputs a cut-off signal, which controls the first
switching circuit to cut off the connection between the ground side
and the coil, to the first switching section, and outputs a
short-circuit signal, which controls the second switching circuit
to connect the two ends of the coil to the driving power supply
side and short-circuit the two ends, to the second switching
section.
8. The semiconductor device of claim 6, wherein the emergency stop
section outputs a cut-off signal, which controls the second
switching circuit to cut off the connection between the driving
power supply side and the coil, to the second switching section,
and outputs a short-circuit signal, which controls the first
switching circuit to connect the two ends of the coil to the ground
side and short-circuit the two ends, to the first switching
section.
9. The semiconductor device of claim 1, wherein the motor is a
brushless motor.
10. A driving mechanism comprising: a semiconductor device; a motor
driving device including a first switching circuit that switches
which of end portions of a coil provided at a motor is connected to
a ground side and a second switching circuit that switches which of
the end portions of the coil is connected to a driving power supply
side, the motor driving device controlling current flowing in the
coil with the first switching circuit and the second switching
circuit; a third switching circuit; and the motor, wherein the
semiconductor device controls the motor driving device, and the
semiconductor device includes: a position detection section that
detects changes in a turning position of a rotor provided at the
motor and outputs detection signals corresponding to the changing
turning position; a first switching section that, in accordance
with the detection signals, outputs ground switching signals, which
switch which end portion of the coil is connected to the ground
side, to the first switching circuit; and a second switching
section that, in accordance with the detection signals, outputs
connection switching signals, which switch which end portion of the
coil is connected to the driving power supply side, to the third
switching circuit, which controls the switching of connections
between the end portions of the coil and the driving power supply
side by the second switching circuit.
11. A motor driving control method at a semiconductor device that
controls a motor driving device, the motor driving device
including: a first switching circuit that switches which of end
portions of a coil provided at a motor is connected to a ground
side; and a second switching circuit that switches which of the end
portions of the coil is connected to a driving power supply side,
the motor driving device controlling current flowing in the coil
with the first switching circuit and the second switching circuit,
and the motor driving control method comprising: detecting changes
in a turning position of a rotor provided at the motor and
outputting detection signals corresponding to the changing turning
position; in accordance with the detection signals, outputting
ground switching signals, which switch which end portion of the
coil is connected to the ground side, to the first switching
circuit; and in accordance with the detection signals, outputting
connection switching signals, which switch which end portion of the
coil is connected to the driving power supply side, to a third
switching circuit that controls the switching of connections
between the end portions of the coil and the driving power supply
side by the second switching circuit.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based on and claims priority under 35
USC 119 from Japanese Patent Application No. 2012-162939 filed on
Jul. 23, 2012, the disclosure of which is incorporated by reference
herein.
BACKGROUND
[0002] 1. Technical Field
[0003] The present invention relates to a semiconductor device, a
driving mechanism and a motor driving control method.
[0004] 2. Related Art
[0005] A technology is disclosed in, for example, Japanese Patent
Application Laid-Open (JP-A) No. 6-165568, that controls driving of
a motor using a semiconductor device such as a microcontroller or
the like. In JP-A No. 6-165568, a microcontroller, a driver circuit
and a position detection circuit are used to control switching
elements of a driving circuit (an upper arm and a lower arm) and
control turning of a brushless motor.
[0006] In JP-A No. 2002-165476, a technology is disclosed that,
without using a driver circuit, controls switching elements of a
driving circuit (an upper arm and a lower arm), and controls
turning of a motor and controls a power supply, with only a
microcontroller and a position detection circuit.
[0007] In a motor, torque and the like is controlled by a current
quantity flowing in a field coil in the motor. If, for some reason,
control of the current flowing in the field coil becomes
impossible, a serious accident may result. Therefore, when it
becomes impossible to control current flowing in a field coil,
current flowing in the field coil must be cut off immediately as a
safety measure.
[0008] In general, if a motor is being driven and electrification
of the motor stops while the motor is turning, current remaining in
the coil produces a back electromotive force and the potential of a
power supply is raised. When the potential of the power supply is
raised, the withstand voltages of components connected to the power
supply may be exceeded and these components may be damaged.
[0009] In order to solve this problem, in driving control of a
brushless motor that uses a related art microcontroller, if an
overcurrent in the brushless motor is detected and should be
stopped, an interrupt is inputted from a comparator detecting the
current to a central processing unit (CPU). Hence, a transistor of
a lower arm that controls electrification between the brushless
motor and ground is turned off, and a transistor of an upper arm
that controls electrification between the brushless motor and a
power supply is turned on. Thus, the two ends of the coil are
short-circuited and the current is regenerated, induced current
remaining in the coil is discharged, the back electromotive force
is suppressed, and damage to components connected to the power
supply is prevented.
[0010] However, in this case, processing of the interrupt from the
comparator that detects the current must be processed in software
by the CPU. Consequently, there is a time lag, the back
electromotive force may not be suppressed immediately, and there is
a danger of damage being caused to components by the back
electromotive force.
[0011] JP-A No. 2007-028694 discloses a technology relating to a
technology that controls driving of a three-phase AC motor by a
rotary electric machine control device constituted with an
integrated circuit. If, for some reason, it becomes impossible to
control current flowing in the field coil of the rotary electric
machine, the current flowing in the field coil is immediately cut
off as a safety measure. Specifically, when it becomes impossible
to control the current flowing in the field coil of the rotary
electric machine for some reason, a PMOS transistor and an NMOS
transistor that are connected in series with the field coil are cut
off by control from the microcontroller.
[0012] Further still, JP-A No. 2003-335456 discloses a technology
in which the value of a current flowing in a motor is compared with
a pre-specified target current value by a comparator. If the value
of the current flowing in the motor exceeds the target current
value, control signals from a CPU are cut off and signals for
controlling the value of current flowing in the motor are outputted
directly to a driving circuit. Thus, when current changes are large
reversals or the like, changes in current value relative to the
target current value are suppressed.
SUMMARY
[0013] A first aspect of the present disclosure is a semiconductor
device that controls a motor driving device. The motor driving
device includes: a first switching circuit that switches which of
end portions of a coil provided at a motor is connected to a ground
side; and a second switching circuit that switches which of the end
portions of the coil is connected to a driving power supply side.
The motor driving device controls current flowing in the coil with
the first switching circuit and the second switching circuit. The
semiconductor device includes: a position detection section that
detects changes in a turning position of a rotor provided at the
motor and outputs detection signals corresponding to the changing
turning position; a first switching section that, in accordance
with the detection signals, outputs ground switching signals, which
switch which end portion of the coil is connected to the ground
side, to the first switching circuit; and a second switching
section that, in accordance with the detection signals, outputs
connection switching signals, which switch which end portion of the
coil is connected to the driving power supply side, to a third
switching circuit that controls the switching of connections
between the end portions of the coil and the driving power supply
side by the second switching circuit.
[0014] A second aspect of the present disclosure is a driving
mechanism that includes: a semiconductor device; a motor driving
device including a first switching circuit that switches which of
end portions of a coil provided at a motor is connected to a ground
side and a second switching circuit that switches which of the end
portions of the coil is connected to a driving power supply side,
the motor driving device controlling current flowing in the coil
with the first switching circuit and the second switching circuit;
a third switching circuit; and the motor, wherein the semiconductor
device controls the motor driving device, and the semiconductor
device includes: a position detection section that detects changes
in a turning position of a rotor provided at the motor and outputs
detection signals corresponding to the changing turning position; a
first switching section that, in accordance with the detection
signals, outputs ground switching signals, which switch which end
portion of the coil is connected to the ground side, to the first
switching circuit; and a second switching section that, in
accordance with the detection signals, outputs connection switching
signals, which switch which end portion of the coil is connected to
the driving power supply side, to the third switching circuit,
which controls the switching of connections between the end
portions of the coil and the driving power supply side by the
second switching circuit.
[0015] A third aspect of the present disclosure is a motor driving
control method at a semiconductor device that controls a motor
driving device. The motor driving device includes: a first
switching circuit that switches which of end portions of a coil
provided at a motor is connected to a ground side; and a second
switching circuit that switches which of the end portions of the
coil is connected to a driving power supply side, the motor driving
device controlling current flowing in the coil with the first
switching circuit and the second switching circuit. The motor
driving control method includes: detecting changes in a turning
position of a rotor provided at the motor and outputting detection
signals corresponding to the changing turning position; in
accordance with the detection signals, outputting ground switching
signals, which switch which end portion of the coil is connected to
the ground side, to the first switching circuit; and in accordance
with the detection signals, outputting connection switching
signals, which switch which end portion of the coil is connected to
the driving power supply side, to a third switching circuit that
controls the switching of connections between the end portions of
the coil and the driving power supply side by the second switching
circuit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a circuit diagram showing a structural example of
a semiconductor device in accordance with an exemplary embodiment
and a structural example of a driving mechanism equipped with this
semiconductor device;
[0017] FIG. 2 is a timing chart showing an example of operation of
the semiconductor device of FIG. 1;
[0018] FIG. 3 is a circuit diagram showing another structural
example of the semiconductor device in accordance with an exemplary
embodiment and a structural example of a driving mechanism equipped
with this semiconductor device;
[0019] FIG. 4 is a timing chart showing an example of operation of
the semiconductor device of FIG. 3;
[0020] FIG. 5 is a timing chart showing another example of
operation of the semiconductor device of FIG. 3; and
[0021] FIG. 6 is a flowchart showing an example of operation of the
semiconductor device in accordance with the exemplary
embodiment.
DETAILED DESCRIPTION
[0022] Herebelow, an exemplary embodiment of the present invention
is described using the attached drawings. FIG. 1 shows the
structure of a driving mechanism 20 that is equipped with a
semiconductor device 1 (which is referred to hereinafter as a
microcontroller) in accordance with a present exemplary embodiment
(a first exemplary embodiment). The semiconductor device 1 (a
one-chip microcontroller) is structured on one chip with a CPU 2, a
random access memory (RAM) 3 and a read-only memory (ROM) 4, and
with a comparator (a) 5, a comparator controller (a) 6 and a pulse
width modulator (PWM) 7. The CPU 2 carries out various kinds of
processing including driving control of a motor 10 provided at the
driving mechanism 20, in accordance with the execution of programs.
The RAM 3 is used as a work area when various programs are being
executed by the CPU 2 and the like. The ROM 4 is a recording medium
in which various processing control programs, various parameters
and the like are memorized in advance. The comparator (a) 5 is
formed of an analog circuit and serves as a position detection
section according to the present invention. The comparator
controller (a) 6 is formed of a logic circuit and serves as a
second switching section according to the present invention. The
PWM 7 outputs pulse width modulation (PWM) pulses and serves as a
first switching section according to the present invention.
[0023] In the present exemplary embodiment (a first exemplary
embodiment), as an example, the semiconductor device 1 is driven at
5.0 V DC and a motor 10 that is the target of control is driven at
12.0 V DC. In the present exemplary embodiment, the motor 10 is a
single-phase brushless motor.
[0024] The driving mechanism 20 is equipped both with the
semiconductor device 1 and the motor 10 and with an upper arm 12
and a lower arm 13. The upper arm 12 is provided with PMOS
transistors T1 and T2, and serves as a second switching circuit
according to the present invention. The lower arm 13 is provided
with NMOS transistors T5 and T6, and serves as a first switching
circuit according to the present invention. A coil 10a and a Hall
effect device 10b are provided in the motor 10. The Hall effect
device 10b detects changes in rotation of the motor 10. In this
motor 10, the coil 10a is fixed, and the motor 10 is turned by
magnetic force generated by current flowing in the coil 100a and
magnetic force from a magnet or the like provided at a rotor of the
motor 10.
[0025] The respective drains of the PMOS transistors T1 and T2
provided in the upper arm 12 are connected, via a diode 11, to a
driving power supply VDDH (12.0 V DC) that is for driving the motor
10. The supply of the PMOS transistor T1 is connected to an end
portion M- of the coil 10a in the motor 10 and to the drain of the
NMOS transistor 15 provided in the lower arm 13. The source of the
PMOS transistor T2 is connected to an other end portion M+ of the
coil 10a in the motor 10 and to the drain of the NMOS transistor T6
provided in the lower arm 13.
[0026] The gate of the PMOS transistor T1 is connected to the
driving power supply VDDH via a resistance R2 and the diode 11, is
connected to the drain of an NMOS transistor T3, which serves as a
third switching circuit according to the present invention, and is
connected to ground GND via this NMOS transistor T3. The gate of
the PMOS transistor T2 is connected to the driving power supply
VDDH via a resistance R1 and the diode 11, is connected to the
drain of an NMOS transistor T4, which is also the third switching
circuit according to the present invention, and is connected to the
ground GND via this NMOS transistor 14.
[0027] That is, the drain of the NMOS transistor T3 is connected to
the gate of the PMOS transistor T1 and the source of the NMOS
transistor T3 is connected to the ground GND, and the drain of the
NMOS transistor T4 is connected to the gate of the PMOS transistor
T2 and the source of the NMOS transistor T4 is connected to the
ground GND. The gate of the NMOS transistor T3 is connected to an
output terminal of the comparator controller (a) 6 of the
semiconductor device 1, and the NMOS transistor T3 is controlled to
turn on and off by a signal UAD0 outputted from the comparator
controller (a) 6. The gate of the NMOS transistor T4 is connected
to another output terminal of the comparator controller (a) 6 of
the semiconductor device 1, and the NMOS transistor T4 is
controlled to turn on and off by a signal UAD1 outputted from the
comparator controller (a) 6.
[0028] The drain of the NMOS transistor T5 provided in the lower
arm 13 is connected to the source of the PMOS transistor T1
provided in the upper arm 12 and to the end portion M- of the coil
10a in the motor 10, and the source of the NMOS transistor T5 is
connected to the ground GND.
[0029] Similarly, the drain of the NMOS transistor T6 provided in
the lower arm 13 is connected to the source of the PMOS transistor
T2 provided in the upper arm 12 and to the end portion M+ of the
coil 10a in the motor 10, and the source of the NMOS transistor T6
is connected to the ground GND.
[0030] The gate of the NMOS transistor T5 provided in the lower arm
13 is connected to an output terminal of the PWM 7 of the
semiconductor device 1, and the NMOS transistor T5 is controlled to
turn on and off by a signal LAD1 outputted from the PWM 7. The gate
of the NMOS transistor T6 provided in the lower arm 13 is connected
to another output terminal of the PWM 7 of the semiconductor device
1, and the NMOS transistor T6 is controlled to turn on and oil by a
signal LAD0 outputted from the PWM 7.
[0031] In practice, diodes are connected between the respective
drains and sources of the PMOS transistors T1 and T2 and the NMOS
transistors T3 to T6.
[0032] The comparator (a) 5 corresponds to a position detection
section of the present invention. The comparator (a) 5 inputs
position detection signals HALL+ and HALL- that are outputted from
the Hall effect device 10b, detects changes in turning positions of
the rotor provided at the motor 10, and outputs detection signals
corresponding to the changing rotary positions.
[0033] The lower arm 13 corresponds to the first switching circuit
of the present invention, and the PWM 7 corresponds to the first
switching section of the present invention. In accordance with the
detection signals outputted from the comparator (a) 5 serving as
the position detection section, the PWM 7 outputs the signals LAD0
and LAD1, which serve as first switching signals, for controlling
the lower arm 13 so as to switch which of the end portions M+ and
M- of the coil 10a of the motor 10 is connected to the ground
GND.
[0034] The upper arm 12 corresponds to the second switching circuit
of the present invention, and the comparator controller (a) 6
corresponds to the second switching section of the present
invention. In accordance with the detection signals outputted from
the comparator (a) 5 serving as the position detection section, the
comparator controller (a) 6 outputs the signals UAD0 and UAD1,
which serve as second switching signals, for controlling the upper
arm 12 so as to switch which of the end portions M+ and M- of the
coil 10a of the motor 10 is connected to the driving power supply
VDDH.
[0035] Thus, connections from the end portions M+ and M- of the
coil 10a of the motor 10 are switched between the driving power
supply VDDH and ground GND by the upper arm 12 and the lower arm 13
on the basis of the detection signals outputted from the comparator
(a) 5. Thus, the direction of a current flowing in the coil 10a of
the motor 10 is switched, and the motor 10 is controlled so as to
turn in one direction.
[0036] For example, when the position detection signal HALL+
outputted from the Hall effect device 10b changes to low (L) and
the signal HALL- changes to high (H), the output of the comparator
(a) 5 goes to low (L), and when the position detection signal HALL+
outputted from the Hall effect device 10b changes to high and the
signal HALL- changes to low, the output of the comparator (a) 5
goes to high. The output from the comparator (a) 5 is inputted to
the PWM 7 and to the comparator controller (a) 6.
[0037] When the output from the comparator (a) 5 changes from high
to low or from low to high, the operation state of the PWM 7 goes
into a stopped state and waits for the input of a start signal from
the CPU 2.
[0038] The CPU 2 applies control such that the output of the
signals LAD0 and LAD1 from the PWM 7 is delayed for a pre-specified
duration after the output from the comparator (a) 5 has changed.
That is, a dead time is specified at the CPU 2 in order to avoid
problems that would occur if the upper arm 12 and the lower arm 13
were turned on at the same time.
[0039] For example, when the output from the comparator (a) 5
changes from high to low and the dead time specified by the CPU 2
has passed, the PWM 7 is put into an operating state, and the
signal LAD0 is set to high. The PWM 7 outputs PWM pulses. The
turning speed of the motor 10 is controlled according to the width
of the pulses.
[0040] In the present exemplary embodiment, in the state in which
the PWM 7 is not operating, the comparator controller (a) 6 sets
the signal UAD1 to low and sets the signal UAD0 to low, regardless
of outputs from the comparator (a) 5.
[0041] When the PWM 7 goes into an operating state, the comparator
controller (a) 6 switches the signal UAD1 or the signal UAD0.
[0042] For example, when the output of the comparator (a) 5 changes
from high to low and the PWM 7 goes into the operating state, the
comparator controller (a) 6 sets the signal UAD0 to high.
[0043] Accordingly, when the signal UAD0 from the comparator
controller (a) 6 goes to high, the NMOS transistor T3 turns on and
the PMOS transistor T1 turns on. In this state, the signal UAD1
from the comparator controller (a) 6 is low, so the NMOS transistor
T4 is turned off and the PMOS transistor T2 is turned off.
[0044] Furthermore, in this state the signal LAD1 outputted from
the PWM 7 is low, so the NMOS transistor T5 is turned off, and the
signal LAD0 outputted from the PWM 7 is high, so the NMOS
transistor T6 is turned on.
[0045] As a result, the end portion M- of the coil 10a of the motor
10 is connected to the driving power supply VDDH via the PMOS
transistor T1 and the diode 11, and the end portion M+ of the coil
10a of the motor 10 is connected to the ground GND via the NMOS
transistor T6. Thus, the motor 10 turns. This turning is rotation
in a forward direction.
[0046] When the motor 10 is turning in the forward direction in
this manner and reaches a predetermined turning angle, which is a
position at which the relationship between the magnetic poles of a
magnet provided at the rotor of the motor 10 and the magnetic poles
of magnetism generated by the coil 10a will retard the turning of
the motor 10, the position detection signal HALL+ outputted from
the Hall effect device 10b changes to high and the signal HALL-
changes to low. At this time, the output of the comparator (a) 5
goes to high, and this high output from the comparator (a) 5 is
inputted to the PWM 7 and the comparator controller (a) 6.
[0047] When the output from the comparator (a) 5 changes from low
to high, the PWM 7 immediately sets the signal LAD0 to low, and
after the dead time has passed, sets the signal LAD to high,
outputting a PWM pulse.
[0048] When the output from the comparator (a) 5 changes from low
to high, the comparator controller (a) 6 immediately sets the
signal UAD0 to low and thereafter, in response to the start of
operation of the PWM 7, sets the signal UAD1 to high.
[0049] Accordingly, when the signal UAD1 from the comparator
controller (a) 6 goes to high, the NMOS transistor 1T4 turns on and
the PMOS transistor T2 turns on. In this state, the signal UAD0
from the comparator controller (a) 6 is low, so the NMOS transistor
T3 is off and the PMOS transistor T1 is off.
[0050] Furthermore, in this state the signal LAD1 outputted from
the PWM 7 is high, so the NMOS transistor T5 is turned on, and the
signal LAD0 outputted from the PWM 7 is low, so the NMOS transistor
T6 is turned off.
[0051] As a result, the end portion M+ of the coil 10a of the motor
10 is connected to the driving power supply VDDH via the PMOS
transistor T2 and the diode 11, the end portion M- of the coil 10a
of the motor 10 is connected to the ground GND via the NMOS
transistor T5, the direction of the current flowing in the coil 10a
switches to the opposite direction from the previous direction, and
the magnetic poles of the magnetism generated by the coil 10a are
reversed. Hence, the motor 10 continues to turn in the forward
direction.
[0052] When the motor 10 is turning in the forward direction in
this manner and reaches a predetermined turning angle, the position
detection signal HALL+ outputted from the Hall effect device 10b
changes back to low and the signal HALL- changes back to high, the
output of the comparator (a) 5 goes to low, and the motor 10
continues to turn in the forward direction.
[0053] That is, in the present exemplary embodiment, the PMOS
transistors T1 and T2 are provided at the upper arm 12 that is
provided for controlling connections to the driving power supply
VDDH (12.0 V DC), switching the connection between the end portions
M+ and M- of the coil 10a of the motor 10, and the PMOS transistors
T1 and T2 are controlled to be turned on and off via the NMOS
transistors T3 and T14. Thus, driving of the motor 10 that is
driven at 12.0 V DC may be controlled by the semiconductor device 1
that is a microcontroller driven at 5.0 V DC.
[0054] The operation of this semiconductor device 1 according to
the present exemplary embodiment is now described using the timing
chart in FIG. 2. When the semiconductor device 1 is started up, the
comparator controller (a) 6 is started up by the CPU 2, and the
comparator (a) 5 is started up by the comparator controller (a)
6.
[0055] At the timing t1, the position detection signal HALL+
outputted from the Hall effect device 10b changes to low and the
signal HALL- changes to high, and the output of the comparator (a)
5 goes to low.
[0056] The output from the comparator (a) 5 is inputted to the PWM
7 and the comparator controller (a) 6. When the output from the
comparator (a) 5 changes from high to low, the operating state of
the PWM 7 goes into the stopped state, the signal LAD1 is
immediately set to low, and the dead time is set and a start signal
inputted from the CPU 2. The comparator controller (a) 6 sets the
signal UAD1 to low immediately.
[0057] At the timing t2, the dead time of the PWM 7 has passed, the
PWM 7 goes into an operating state, and the signal LAD0 (PWM
pulses) is outputted. When the PWM 7 goes into the operating state,
the comparator controller (a) 6 sets the signal UAD0 to high.
[0058] Thus, when the signal LAD0 (PWM pulses) is outputted from
the PWM 7 and the signal UAD0 from the comparator controller (a) 6
goes high, as described above, the motor 10 turns in the forward
direction.
[0059] At the timing t3, the motor 10 turning in the forward
direction has turned to the predetermined turning angle, the
position detection signal HALL+ outputted from the Fall effect
device 10b changes to high and the signal HALL- changes to low, and
the output of the comparator (a) 5 goes to high.
[0060] The output from the comparator (a) 5 is inputted to the PWM
7 and the comparator controller (a) 6. When the output from the
comparator (a) 5 changes from low to high, the operating state of
the PWM 7 goes into the stopped state, the signal LAD0 is
immediately set to low, and the dead time is set and a start signal
inputted from the CPU 2. The comparator controller (a) 6 sets the
signal UAD0 to low immediately.
[0061] At the timing t4, the dead time of the PWM 7 has passed, the
PWM 7 sets the signal LAD1 to high, outputting PWM pulses, and the
comparator controller (a) 6 sets the signal UAD1 to high.
[0062] Thus, when the signal LAD1 (PWM pulses) is outputted from
the PWM 7 and the signal UAD1 from the comparator controller (a) 6
goes high, as described above, the direction of the current flowing
in the coil 10a of the motor 10 changes and the motor 10 continues
to turn in the forward direction.
[0063] At the timing t5, the motor 10 continuing to turn in the
forward direction has turned to the predetermined turning angle,
the position detection signal HALL+ outputted from the Hall effect
device 10b changes to low and the signal HALL- changes to high, the
output of the comparator (a) 5 goes low, and operations are the
same as at the timing t1. At the timing t6, operations are the same
as at the timing t2, and these same operations are repeated
thereafter.
[0064] Now, another exemplary embodiment (a second exemplary
embodiment) is described using FIG. 3, FIG. 4 and FIG. 5.
[0065] A driving mechanism 20a shown in FIG. 3 has a structure in
which resistances R3 and R4 and a capacitor C1 are added to the
driving mechanism 20 shown in FIG. 1, and in a semiconductor device
1a, a logic circuit comparator controller (b) 8 and an analog
circuit comparator (b) 9 are added to the semiconductor device
1.
[0066] Structures other than the resistances R3 and R4 and
capacitor C1 and the comparator controller (b) 8 and comparator (b)
9 in the semiconductor device 1a are the same as in the driving
mechanism 20 in FIG. 1, and operations thereof are not described
here.
[0067] The resistance R4 is connected between the respective
sources of the NMOS transistors T3 to T6 and the ground GND.
Current values flowing in the resistance R4, that is, current
values flowing in the motor 10, are measured by the resistance R3
and the capacitor C1.
[0068] The comparator controller (b) 8 corresponds to an emergency
stop section of the present invention, and the comparator (b) 9
corresponds to an overcurrent detection section of the present
invention.
[0069] In this structure, the current values flowing in the motor
10 that are measured by the resistance R3 and capacitor C1 are
inputted to the comparator (b) 9. The comparator (b) 9 compares the
inputted current values (CS_I) with a pre-specified reference
value. When a current with an abnormal value exceeding the
reference value (an overcurrent) flows in the motor 10, the
comparator (b) 9 outputs an overcurrent detection signal. In this
case, the current value is converted to a voltage value, inputted
to the comparator (b) 9, and compared with a reference voltage at
the comparator (b) 9.
[0070] The overcurrent detection signal outputted from the
comparator (b) 9 is inputted to the comparator controller (b) 8,
and the comparator controller (b) 8 outputs an emergency stop
signal CS_O to the PWM 7 and the comparator controller (a) 6, so as
to urgently stop the turning of the motor 10.
[0071] In the present exemplary embodiment, the comparator
controller (b) 8 outputs signals that control the PWM 7 and the
comparator controller (a) 6 so as to short-circuit (connect
together) the two ends of the coil 10a, so as to stop
electrification of the coil 10a of the motor 10 and regenerate
current remaining in the coil 10a.
[0072] For example, the comparator controller (b) 8 outputs a
cut-off signal to the PWM 7 to control the lower arm 13 and cut off
the connection between the ground GND and the coil 10a, and the
comparator controller (b) 8 outputs a short-circuit signal to the
comparator controller (a) 6 to control the upper arm 12, connect
the two ends of the coil 10a to the driving power supply VDDH and
short-circuit the coil 10a.
[0073] Alternatively, the comparator controller (b) 8 outputs the
cut-off signal to the comparator controller (a) 6 to control the
upper arm 12 and cut off the connection between the driving power
supply VDDH and the coil 10a, and the comparator controller (b) 8
outputs the short-circuit signal to the PWM 7 to control the lower
arm 13, connect the two ends of the coil 10a to ground and
short-circuit the coil 10a.
[0074] Thus, effects are provided in that a back electromotive
force that is generated when electrification of the motor 10 is
stopped during rotation of the motor 10 may be suppressed, and
hence exceeding of withstand voltages at components connected to a
power supply (the driving power supply VDDH) may be prevented, and
damage to the components may be prevented.
[0075] Operation of this semiconductor device 1a according to the
present exemplary embodiment is now described using the timing
charts in FIG. 4 and FIG. 5. The operations at timings t1 to t6 are
the same as those described with FIG. 2, and are not described
here.
[0076] First, an operational example in which the two ends of the
coil 10a are connected and short-circuited at the upper arm 12 side
is described using FIG. 4. At the timing t7 in FIG. 4, the
comparator (b) 9 detects that an overcurrent is flowing in the
motor 10 (the coil 10a), and the comparator (b) 9 outputs the
overcurrent detection signal (high).
[0077] When the comparator (b) 9 outputs the overcurrent detection
signal (high), the comparator controller (b) 8 outputs the
emergency stop signal CS_O to the PWM 7, and operation of the PWM 7
is immediately emergency-stopped.
[0078] When the PWM 7 inputs the emergency stop signal CS_O from
the comparator controller (b) 8, operation of the PWM 7 stops
(PWM_STAT goes low), and the output signals LAD0 and LAD1 are both
set to low.
[0079] When the PWM 7 emergency-stops and PWM_STAT goes low, the
emergency stop signal is inputted from the PWM 7 to the comparator
controller (a) 6, and the comparator controller (a) 6 sets both the
output signals UAD0 and UAD1 to high.
[0080] Thus, when the output signals UAD0 and UAD1 from the
comparator controller (a) 6 both go high, the NMOS transistors T3
and T4 in FIG. 3 are both turned on, so the PMOS transistors T1 and
T2 provided at the upper arm 12 are both turned on. Meanwhile, the
output signals LAD0 and LAD1 from the PWM 7 are both low, so the
NMOS transistors T5 and T6 provided at the lower arm 13 in FIG. 3
are both turned off.
[0081] As a result, the two end portions M+ and M- of the coil 10a
of the motor 10 are short-circuited via the PMOS transistors T1 and
T2, and the current remaining in the coil 10a is regenerated. Thus,
a current may be regenerated and a back electromotive force
suppressed without a time lag.
[0082] Next, an operational example in which the two ends of the
coil 10a are connected and short-circuited at the lower arm 13 side
is described using FIG. 5. At the timing t7 in FIG. 5, the
comparator (b) 9 detects that an overcurrent is flowing in the
motor 10 (the coil 10a), and the comparator (b) 9 outputs the
overcurrent detection signal (high).
[0083] When the comparator (b) 9 outputs the overcurrent detection
signal (high), the comparator controller (b) 8 outputs the
emergency stop signal CS_O to the PWM 7, and operation of the PWM 7
is immediately emergency-stopped.
[0084] When the PWM 7 inputs the emergency stop signal CS_O from
the comparator controller (b) 8, operation of the PWM 7 stops
(PWM_STAT goes low), and the output signals LAD0 and LAD1 are both
set to high.
[0085] When the PWM 7 emergency-stops, PWM_STAT goes low and the
emergency stop signal is inputted from the PWM 7 to the comparator
controller (a) 6, the comparator controller (a) 6 sets both the
output signals UAD0 and UAD1 to low.
[0086] Thus, when the output signals UAD0 and UAD1 from the PWM 7
both go low, the NMOS transistors T3 and T4 in FIG. 3 are both
turned off, so the PMOS transistors T1 and T2 provided at the upper
arm 12 are both turned off. Meanwhile, the output signals LAD0 and
LAD1 from the PWM 7 are both high, so the NMOS transistors T5 and
T6 provided at the lower arm 13 in FIG. 3 are both turned on.
[0087] As a result, the two end portions M+ and M- of the coil 10a
of the motor 10 are short-circuited via the NMOS transistors T5 and
T6, and the current remaining in the coil 10a is regenerated. Thus,
a current may be regenerated and a back electromotive force
suppressed without a time lag.
[0088] In the emergency stop operations described with FIG. 4 and
FIG. 5, when the PWM 7 emergency-stops, an emergency stop flag is
set to high. This emergency stop flag may be cleared by a register
write by the CPU 2, and usual operations are resumed after this
write.
[0089] Now, motor driving control operations in accordance with the
exemplary embodiment of the semiconductor device 1 in FIG. 1 are
described using FIG. 6. When, in accordance with the outputs of the
Hall effect device 10b, the comparator (a) 5 detects that the
turning position of the rotor provided at the motor 10 has changed
to a predetermined turning angle (step 601), the comparator (a) 5
outputs a detection signal (high/low) (step 602).
[0090] When the detection signal (high/low) is outputted from the
comparator (a) 5, the PWM 7 outputs switching signals (LAD0 and
LAD1) in accordance with the detection signal (high/low) to the
lower arm 13 to switch which end portion of the coil 10a is
connected to the ground GND (step 603), and the comparator
controller (a) 6 outputs switching signals (UAD0 and UAD1) in
accordance with the detection signal (high/low), to switch which
end portion of the coil 10a is connected to the driving power
supply VDDH at the upper arm 12, to the NMOS transistors T3 and T4
corresponding to the third switching circuit of the present
invention (step 604).
[0091] In the present exemplary embodiment, the comparator
controller (a) 6 controls to turn the PMOS transistors T1 and T2
provided at the upper arm 12 on and off via the NMOS transistors T3
and T4.
[0092] The detection signals (high/low) outputted from the
comparator (a) 5 are microcontroller outputs. Thus, according to
the present exemplary embodiment, the motor 10 that is driven at
12.0 V DC may be controlled by the semiconductor device 1 that is a
microcontroller driven at 5.0 V DC.
[0093] During the operation of the above-mentioned steps 601 to
604, if an overcurrent detection signal (high) is outputted from
the comparator (b) 9 shown in FIG. 3, the emergency stop operation
that has been described using FIG. 4 and FIG. 5 is carried out, the
two end portions M+ and M- of the coil 10a are short-circuited, and
a back electromotive force may be suppressed by current remaining
in the coil 10a being regenerated.
[0094] As has been described hereabove using the drawings, in the
driving mechanism 20 or 20a equipped with the semiconductor device
1 or 1a according to the present exemplary embodiments, driving of
the motor 10 that is driven at 12.0 V DC may be controlled by the
semiconductor device 1 or 1a with a one-chip microcontroller
structure that is driven at 5.0 V DC.
[0095] Furthermore, if an overcurrent flows in the motor 10, the
overcurrent detection signal (high) is outputted from the
comparator (b) 9, the emergency stop operation is carried out, and
the two end portions M+ and M- of the coil 10a are short-circuited.
Thus, the current remaining in the coil 10a may be regenerated and
a back electromotive force suppressed without a time lag, and
damage to components from the back electromotive force may be
avoided.
[0096] The present invention is not limited to the exemplary
embodiments described using the drawings, and numerous
modifications are possible within a technical scope not departing
from the spirit of the invention. For example, in the present
exemplary embodiments, the semiconductor device 1 or 1a is driven
at 5.0 V DC and the motor 10 that is the control target is driven
at 12 V DC. However, the semiconductor device 1 or 1a may be driven
at 3.3 V DC and the motor 10 may be driven at 24 V DC. Further, the
motor 10 is a single-phase brushless motor in the present exemplary
embodiments, but the present invention is also applicable to
three-phase brushless motors and so forth.
[0097] In recent years, with the objective of saving electric power
at microcontrollers, progress has been made in reducing voltages.
Thus, there is a need, just with a microcontroller with a low
driving voltage, to efficiently control a motor with a high driving
voltage, and to detect an overcurrent in a motor and efficiently
stop the motor.
[0098] In the aforementioned JP-A No. 2002-165476, switching
elements of driving circuits (an upper arm and a lower arm) are
controlled and turning of a motor is controlled with just a
microcontroller and a position detection circuit. However, in JP-A
No. 2002-165476, position detection signals outputted from a
position detection signal generation circuit are converted to
digital signals by an A/D converter, after which the position of a
rotor of the motor is calculated using the digital signals by
arithmetic processing at a CPU. Therefore, it takes time to detect
the turning position of the motor, and a high-performance
microcontroller that is capable of high-speed arithmetic processing
is required to control a motor with a high rate of rotation. In
addition, because the area of an A/D converter circuit is large,
this technology is not preferable in regard to reducing circuit
area.
[0099] Further, in a conventional technology that detects an
overcurrent in a motor and stops turning of the motor just with a
microcontroller, processing of an interrupt from a comparator that
detects the current must be processed in software by a CPU.
Therefore, there is a time lag, a back electromotive force may not
be suppressed immediately, and there is a danger of damage to
components from the back electromotive force.
[0100] In the technology recited in JP-A No. 2003-335456, when a
current change is a large reversal or the like, a change in current
value relative to a target current value is suppressed. Thus, an
overcurrent in the motor is not detected and turning of the motor
is not stopped immediately.
[0101] According to the present invention, driving of a motor may
be efficiently controlled using a microcontroller with a lower
driving voltage than the motor.
* * * * *